Developmental research has demonstrated infants' ability to monitor goals and intentions as early as 8 months old, yet research consistently reveals that adult perspective taking is cognitively effortful and error prone. Several recent studies have tested a two-system theory, whereby a relatively quick, heuristic process tracks the basic visuospatial perspective of others, while a relatively slow, effortful process selects and evaluates the belief states leading to higher-level theory of mind. However, experiments supporting two systems have consistently equated spatial perspective taking with gaze direction. In a psychophysical paradigm, participants were rapidly cued to take their own or an avatars' perspective, and judged whether that perspective could see a number of objects within the range of subitization. In some trials, the avatar's view was obstructed by a barricade. Reaction time and error rate rose significantly when self and other views conflicted, even when taking one's own perspective. Results support a heuristic mechanism that quickly assess the content of another's perspective.